Vibratory tamper



United States Patent Ave,

This invention relates to a vibratory tamper adapted for use in tampingplastic material prior to setting and curing. The tamper is particularlyadapted for use in tamping concrete while in a plastic or amorphic stateand permits a combined tamping and smoothing operation to be performedby a single workman.

Previously available tampers for plastic substances, such as concreteand the like, merely provided a tamping element connected to a source ofpower to effect reciprocation of the element. Certain of the prior artdevices included a crank and connecting rod or similar eccentric drivemechanism between the source of power and the tamping element to impartthe desired reciprocating movement to the tamping element. An inherentcharacteristic of such power transmission mechanisms is a lateral thrustcomponent in the force transmitted to the tamping element, the amplitudeof the lateral thrust being dependent upon the length of the crank, orthe eccentricity of the drive mechanism. Consequently, vibrationssubstantially normal to the direction of reciprocation of the tampingelement are incurred by such tampers.

In certain prior art tampers, such vibrations are horizontally orientedand are utilized in floating or smoothing the concrete by laterallyopposed floating shoes rigidly connected to the framework of the tamper.A specific example of such a construction is illustrated in UnitedStates Patent No. 2,746,367 to Ferguson. In many operationalenvironments the vibrations in a horizontal plane have not been found tobe desirable in tamping and floating of the concrete, and unnecessarilyadd to the total vibration of the assembled machine. Consequently,workmen operating such machines are subjected to enervating andfatiguing vibrations. In addition, the requisite laterally opposed pairof shoes are necessary to balance the vibrations imparted to the shoesthrough the framework. Consequently, such a construction precludes acombined tamping and floating or smoothing operation, and unnecssarilyadds to the total mass of the machine.

Accordingly, it is an object of the present invention to provide avibratory tamper which includes a power transmission mechanism whicheliminates or minimizes undesirable vibratons occurring in a generallyhorizontal plane.

Another object is to provide a vibratory tamper which permits thesimultaneous performance of tamping and smoothing operations by a singleworkman.

Another object is to provide a tamper having a tamping element mountedfor reciprocation in a generally vertical plane of movement and providedwith resilient connecting means in the power train to absorb a majorportion of the vibrations otherwise transmitted to the workman operatingthe tamper.

Other objects and advantages of the present invention will subsequentlybecome more clearly apparent upon reference to the description in thespecification.

In the drawing:

FIG. 1 is a top plan view of the vibratory tamper of the presentinvention with portions broken away for illustrative convenience.

FIG. 2 is a rear elevation of the vibratory tamper of FIG. 1.

FIG. 3 is a transverse vertical section through the tamper taken on line3-3 of FIG. 2.

Referring more particularly to the drawing, a vibratory tamper embodyingthe principles of the present invention provides a frame generallyindicated at 10 having an elongated substantially rectangular base plate11 of substantially rigid sheet material, such as aluminum, stainlesssteel or the like. The frame includes a pair of upstanding pedestals 14,each having a lower mounting flange 15, a pair of lower oppositelyspaced boss members 16 having bores 17 and an upper pillow block bearingmounting structure 18. The pillow block structure includes an upperbearing cap 1 constrained on the pedestal by bolt and nut assemblies 2G.The frame further provides a manually engageable inverted substantiallyU-shaped handle 22 having lower mounting ends 23 disposed in over-lyingrelation to the flanges 15 of the pedestals 14.

An elongated float shoe 25 having a leading portion 26 and a trailingportion 27 is closely associated with the above described framecomponents. The leading portion of the shoe provides a top wall 30 whichis disposed between the mounting flanges 15 of the pedestals 14 and thebase plate 11. The lower mounting ends 23 of the handle 22, the flanges15 and the base plate 11 are interconnected by bolt and nut assemblies32 extended therethrough, as shown in FIG. 2. The leading portion 26 ofthe shoe further includes depending spaced substantially parallel sidewalls 36 having forward and rearward lower edges 37 and 38,respectively, disposed in substantially horizontal coplanar relation.The top and side walls thereby cooperate to define an elongateddownwardly opening channel 39. The trailing portion 27 of the shoeprovides a trowel member at} integrally rearwardly extended from therearward lower edge 38 and has a lower substantially planar surface 42in coplanar relation with the edges.

An elongated drive shaft 45 is rotatably mounted at its ends in bearings46 mounted in the pillow blocks 18 of the spaced pedestals 14 inupwardly spaced substantially parallel relation to the top wall 34 ofthe float shoe 25. The drive shaft includes extended end portions 47disposed transversely outwardly of the bearings. A pulley wheel 50 ismounted on the drive shaft adjacent to one end thereof for mounting aV-belt 52. The V-belt is trained about a drive pulley 54- mounted on thedrive shaft 55 of a motor 56 of any suitable form, such as an internalcombustion engine, as illustrated. The motor is mounted on a supportplate 60 mounted on the top wall 30 of the shoe intermediate its ends bya plurality of bolt and nut assemblies 62. The support plate includes arearwardly overhanging motor mounting portion 64 having a pair ofdepending legs 65 of resilient material, such as rubber or the like,engageable with the upper surface of the trowel 40. i

A pair of eccentric drive mechanisms, generally indicated by thereference numeral 70, are individually mounted on each of the extendedends 47 of the drive shaft 45 outwardly adjacent to the pillow blocks 18of the pedestals 14. The eccentric drive mechanisms each provide aninner substantially circular throw member 72 eccentrically mounted onthe extended ends of the drive shaft. A roller bearing 74 is mounted incircumscribing relation on the throw member and has an outer race 75providing an integral radially downwardly extended connecting rod 78.The connecting rod provides a lower screw threaded end 79 which mounts apair of opposed adjusting nuts 80 thereon.

A pair of support members or cross heads individually mount a pair ofspaced depending legs or bolts 86 adjacent to their ends which providelower screw threaded ends 87. The lower end 79 of each connecting rod 78is loosely extended through an enlarged bore 88 intermediate the ends ofits respective cross head. A pair of bushings 89 of a diameter largerthan the diameter of the bore 88 and of resiliently flexible material,such as rubber or the like, are disposed on the lower end of theconnecting rod between the adjusting nuts 80 and on opposite sides ofthe cross head. The adjusting nuts are tightened against theirrespective bushings resiliently to couple the connecting rod to thecross head. Elongated spacer sleeves 90 are individually mounted on thebolts for extension through the bores 17 in the boss members 16 of thepedestals and through the top wall 30 of the shoe 25 and the base plate11. A pair of seal members 92 of felt material or the like are disposedabout the sleeves between the boss members 16 and the mounting flanges15 of the pedestals to preclude upward travel of concrete and otherextraneous matter into the bores 17.

An elongated substantially rectangular tamper 94 is provided of a sizeto be received within the channel of the leading portion 26 of the shoe.The tamper includes a rectangular frame 95 having upstanding side walls96 supporting a lower substantially planar reticulated tamping surface97 of expanded metal material or the like. The tamper has a pair ofcross bars 93 providing tapped bores screwed threadably to receive thelower threaded ends 87 of the bolts 86 of the cross head which tightenthe frame 95 of the tamper tightly against the sleeves 90.

Operation The operation of the described embodiment of the subjectinvention is believed to be clearly apparent and is briefly summarizedat this point. After the concrete to be finished has cured sufiicientlyto support a workman, the vibratory tamper of the present invention isdisposed on the surface thereof and the motor 56 started to impartrotation to the drive shaft 45. Such rotation causes eccentric rotarymovement of the throw member 72 which imparts a substantially verticalreciprocating motion to the connecting rod 78. As previously described,such movement-also produces a lateral thrust component proportional tothe eccentricity of the throw member 72 on the drive shaft. Such lateralthrust is, however, absorbed and substantially isolated from the crosshead and tamper by the resilient bushings 89 and unrestricted lateralmovement of the connecting rod within the enlarged bore 88. As a result,the only motion transmitted is the afore described substantiallyvertical reciprocating movement of the cross head which is transmittedby way of the connecting bolts 85 to the tamper 94. The tamper isreciprocated within the channel 39 of the leading portion of the shoeahead of the trowel 40 as the tamper is motivated in a rectilinear pathof travel incident to a pulling force on the forwardly extended handle22 by the workman. During such movement, the concrete can be tamped andimmediately smoothed in a single operation by a single workman.

In view of the foregoing, it is readily apparent that the structure ofthe present invention provides an improved vibratory tamper whichaffords improved control of the device by substantially eliminating thetransfer of undesirable horizontal vibrations to the workman and to thetrowel. portion of the device. With such arrangement, substantially allvibration developed in the drive portion of the device is concentratedfor reciprocating the tamper portion of the device.

Although the invention has been herein shown and described in what isconceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom within the scope of theinvention, which is not to be limited to the details disclosed hereinbut is to be accorded the full scope of the claims so as to embrace anyand all equivalent devices and apparatus.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. A vibratory tamper comprising a support frame; a substantiallyrectangular float shoe having predetermined leading and trailingportions adapted to be propelled in a predetermined substantiallyrectilinear path of travel, said leading portion providing a top wallsection and depending spaced substantially parallel side wall sectionsproviding lower edges with the wall sections defining a downwardlyopening channel, said trailing portion providing a substantially planarsurface disposed in horizontal coplanar relation with said lower edgesof the wall sections and being adapted to contact concrete in a plasticstate and to effect a troweling action during said rectilinear movement;manually engageable handle means rigidly upwardly extended from saidframe; an elongated substantially rectangular tamper having oppositeends affording a substantially planar reticulated tamping surface; guidemeans integral with the frame; a cross head means mounted above said topwall section of the shoe having a central bore formed therein and a pairof elongated spaced depending connecting members symmetrically relatedto said bore and extended in laterally constrained longitudinal slidingrelation through said guide means and through said top wall sectionmounting the tamper within said channel of the leading portion of theshoe in substantially parallel relation to said float surface forrectilinear reciprocating movement in a direction substantially normalto said tamping surface; power means borne by the frame; an eccentricdrive member connected to said power means in driven relationship; aconnecting rod having an upper end connected to said eccentric drivemember and an opposite lower end of a diameter smaller than said bore inthe cross head extended substantially concentrically through the bore;and a pair of resilient couplings connecting said lower opposite end ofthe connecting rod to said cross head means to impart said rectilinearreciprocating movement to said tamper so as to absorb vibrationsoriginating in said eccentric drive member in a plane substantiallynormal to the path of reciprocating movement of the tamper.

2. The vibratory tamper of claim 1 in which said guide means includes apair of spaced boss members on the frame having elongated borestherethrough adjacent to each end of the tamper; said cross head meanscomprises a pair of said cross heads and said connecting memberscomprise a pair of depending legs longitudinally slidable through saidbores of the boss members to preclude lateral rocking of the tamper; andsaid resilient couplings comprising a pair of bushings disposed aboveand below their respective cross heads and being of a diameter largerthan the diameter of the bore thorugh the cross heads, adjusting meansborne by the lower end of said connecting rods adjustably to tighten thebushings against their respective cross heads so as to maintain saidconnecting rods in concentric relation within the bores substantiallycompletely to isolate lateral vibrations emanating in the connecting rodfrom the tamper.

3. A vibratory tamper comprising a support frame; a float shoe mountedon said frame having predetermined leading and trailing portions adaptedto be propelled in a predetermined substantially rectilinear path oftravel, said leading portion providing a downwardly opening channel andsaid trailing portion providing a substantially planar surface adaptedto contact concrete in a plastic state and to effect a troweling actionduring said rectilinear movement; manually engageable handle means rigidly extended from said frame; a tamping member affording a substantiallyplanar tamping surface; a support member having a bore therethrough anda pair of spaced depending legs guided by the frame mounting the tampingmember within said channel of the leading portion of the shoe insubstantially parallel relation to said float surface for rectilinearreciprocating movement in a direction substantially normal to saidtamping surface; power means carried by the frame; reciprocating meansconnected to said power means in driven relationship; a connecting rodhaving one end connected to said reciprocating means and an opposite endextended through said bore in the support member; and resilient meansconnecting said opposite end of the connecting rod to said supportmember to impart said rectilinear reciprocating movement to said tampingelement and to absorb vibrations in a plane substantially normal to thepath of reciprocating movement.

References Cited by the Examiner UNITED STATES PATENTS JACOB L.NACKENOFF, Primary Examiner.

3. A VIBRATORY TAMPER COMPRISING A SUPPORT FRAME; A FLOAT SHOE MOUNTEDON SAID FRAME HAVING PREDETERMINED LEADING AND TRAILING PORTIONS ADAPTEDTO BE PROPELLED IN A PREDETERMINED SUBSTANTIALLY RECTILINEAR PATH OFTRAVEL, SAID LEADING PORTION PROVIDING A DOWNWARDLY OPENING CHANNEL ANDSAID TRAILING PORTION PROVIDING A SUBSTANTIALLY PLANAR SURFACE ADAPTEDTO CONTACT CONCRETE IN A PLASTIC STATE AND TO EFFECT A TROWELING ACTIONDURING SAID RECTILINEAR MOVEMENT; MANUALLY ENGAGEABLE HANDLE MEANSRIGIDLY EXTENDED FROM SAID FRAME; A TAMPING MEMBER AFFORDING ASUBSTANTIALLY PLANAR TAMPING SURFACE; A SUPPORT MEMBER HAVING A BORETHERETHROUGH AND A PAIR OF SPACED DEPENDING LEGS GUIDED BY THE FRAMEMOUNTING THE TAMPING MEMBER WITHIN SAID CHANNEL OF THE LEADING PORTIONOF THE SHOE IN SUBSTANTIALLY PARALLEL RELATION TO SAID FLOAT SURFACE FORRECTILINEAR RECIPROCATING MOVEMENT IN A DIRECTION SUBSTANTIALLY NORMALTO SAID TAMPING SURFACE; POWER MEANS CARRIED BY THE FRAME; RECIPROCATINGMEANS CONNECTED TO SAID POWER MEANS IN DRIVEN RELATIONSHIP; A CONNECTINGROD HAVING ONE END CONNECTED TO SAID RECIPROCATING MEANS